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December 2010 Archives

I wish you all a very Happy Christmas - PhysicsStop will be back in the New Year.

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With regard to the last post, I'd like to clarfiy why I have used the word 'girl' not 'woman' in the title. Many of you have pointed this out to me.

My thought when I began to write this short post was that I was addressing it to girls at school, who were thinking about whether to carry on with science subjects (and physics in particular). Hence the word 'girl' rather than 'woman'. However, on reading the article again, I can see that this intention isn't clear.

I apologize if it has caused any offence.



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[20 December 2010 - Please read the comment about the title here]

I just throw up the following factoids from the Australian Institute of Physics congress. Maybe together they mean something.  Let me know...

1. Not many women do physics at university. (That wasn't from the congress - every physicist knows it)

2. Female students do (slightly) worse at some well-used standard multiple-choice tests such as the 'Force Concept Inventory'.

3. If you ask the question 'Are you Male or Female?' at the beginning of a physics test, female students will do worse in the test. Male students are unaffected. (The hypothesis is that women suddenly think - I'm female - I'm not supposed to do well - then the subconscious takes over to ensure they don't.)

4. A major reason why year 10 students (male or female) choose not to continue in science is that they cannot picture themselves being a scientist. (This has implications for doing outreach programmes aimed at this age group).

5. Eighty-three percent of women holding academic positions in physics (maybe in the US - but I'm not sure) have a husband / partner who is a scientist. (Schiebinger et al. (2008), Institute for Gender Research, Stamford University)

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Consider the following perfectly reasonable sentences:

"It's hot outside"

"The oven is heating up"

"Insulation helps keep a house warm"

Here we have physics words and concepts being used in everyday English in ways that are rather loose from a physics point of view. Does the conventional English use of words such as 'heat', 'temperature', 'insulate', etc confuse students when they come to learn thermodynamics? For example, even a physicist would say "it's hot today", when  he knows what he actually means is "the temperature is high today". In thermodynamics, heat and temperature are very precise concepts, and are not interchangeable, as they often are in English.

Anyway, a study of confusion amongst students caused by conventional English usage of thermodynamics words was the subject of Helen Georgiou's short talk last week at the Australian Institute of Physics congress. Brief conclusion: Yes, there is confusion, and often students aren't aware of where it's coming from.

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No, the Large Hadron Collider hasn't vanished. It might not be so prominent in the news as it was two years ago, but it is quietly colliding protons together and generating lots of useful data for analysis.

Here's a couple of bits which I gleaned in Melbourne

1. What lies inside a quark (if anything?).  Us physicists are happy with the notion that at the centre of an atom lies a nucleus, consisting of protons and neutrons, and each proton and neutron contains three quarks. (For the case of a proton, it's two 'up' quarks and one 'down' quark; for the neutron its two 'down' quarks and one 'up'. Protons and neutrons are actually very, very similar things.)  But is the quark made of anything? How could we tell? Basically, the way you do this is to collide protons together (i.e. 3 quarks on 3 quarks) and carefully analyze the statistics of the scattering. At what angles are the protons scattered? Is there fine-structure in the scattering pattern? This is exactly what Rutherford did with Geiger and Marsden's alpha-particles on gold-foil results to determine that there must be a nucleus to an atom. In the case of the gold-foil, the structure in the pattern is pretty obvious. In the proton-proton case, it's not. In fact, results from the ATLAS experiment at the LHC fail to indicate any structure at current energies (3.4 TeV).  (In particle physics, higher energies equate to probing smaller distances). So we can conclude that IF there is structure (and it's a big if), it must appear at energy scales larger than 3.4 TeV. So far, the quark remains 'fundamental'.

2. Can we find dark matter?  Dark matter is what is thought to make up 23% of the mass/energy of the universe. It has the annoying property that you can't see it - in fact it doesn't interact with any electromagnetic things. So why do we think it's there?  If you study the way galaxies are moving, knowing what we know about gravity, we come to the conclusion that there simply isn't enough visible mass in a galaxy to account for its movement. Galaxies seem to be more massive than we can account for by 'counting' stars in them. This missing mass is called 'dark matter'.  (N.B. There's also dark energy, that makes up about 73% of the universe, which is another thing, but I won't go there today.) So, what is it? We don't know, but there are theories. Moreover, these theories are testable - in that you can use them to make predictions about what might be observed in the LHC. So people are busy analysing results of collisions to see if there are features observed in the LHC that can only be explained by the theories of dark matter. If there are, that's strong evidence for the 'discovery' of dark matter.  I have to say that listening to a couple of talks I was impressed at the size of the research effort on theories of dark matter - given that this stuff hasn't actually been observed yet. It must take a bit of faith to spend your PhD studying something that might not even exist.

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One of my talks last week concerned a piece of work I'd done with my second year experimental physics class this year. Before going to Melbourne, I gave the talk a trial run at the University of Waikato's 'celebrating teaching' day. It provoked a few comments then, and a few more in Melbourne, so I thought I'd give a summary of it here.

I've been teaching experimental physics more or less for the whole time I've been at the university (my divine punishment for navigating my own undergraduate studies on the basis of finding the path with the least amount of practical work in it). I've noticed that few students do any planning before the lab. Some will turn up at the lab without even knowing what experiment they will be trying to do. So this year I've tried to turn this around.


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Back on-line now after a week in Melbourne at the Australian Institute of Physics conference.

I have lots of good stuff to blog about, including optomechanics (using light to cause vibrations), physics education (lots on this), the Large Hadron Collider and complicated models of things that might not even exist, but I'll do this one on climate change.

On Wednesday, we had a very colourful and dynamic plenary lecture by David Kardy, from the University of Melbourne. In short, it was a rant about Ian Plimer's recent book about Climate Change, and how certain high-profile Australian politicians (e.g. leader of the opposition Tony Abbot) like to draw their science from unscientific sources.

Essentially, Prof Kardy went through Ian Plimer's major items of evidence for non-human causes of recent climate change and rebutted them. He covered a lot of ground in a 45 minute talk, which was rather too fast to take in, but the take-home message was that the science says that the bulk of recent warming of the earth's climate is caused by human activities (and not due to Plimeresque magic underwater volcanoes).

Anyway, the most useful part of the talk for me, came in the 'questions' section at the end. Someone stood up and said something along these lines: "I am a physicist but not a climate physicist. What can I do to tackle disinformation in this field?" Prof Kardy's response wasto say that we should help people to see what good science actually was. There has been a lot of good science done on climate change. Kardy suggested that non-climate physicists (like me) look at the booklet "Science of Climate Change - Questions and Answers", published by the Australian Academy of Science. (You may do the same, by clicking the link).

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Last week I took part in a 'Science Sampler Day', at Ruakura in Hamilton. The idea behind this was to take some really good year 9 school children, and give them a day exposed to some real science. This was run by another Hamilton-based scientist Liz Carpenter, and I thought was a great success.

Throughout the day, the children were is small groups and rotated around different science activities. It was intentionally pretty rapid-fire, with each activity only being about 10 minutes in length. That gave the opportunity to sample lots of different areas of science. Examples included strength of materials, water quality, measuring a runner's speed and using an infra-red camera to measure body temperature - very varied but all very exciting too.

I took along some electroencephalogram (brain-waves) recording equipment. I think it turned out to be a good choice of activity - on the one hand it looks quite high-tech and impressive, and I think being wired-up and having your brain waves monitored is quite fun - but also in ten minutes I could use it to illustrate that things the children are already learning at school have real application - notably electricity and circuits, and a bit of maths too.

I was certainly impressed with the range of questions and comments that I got - for example speculating about the uses of this (e.g. monitoring of anaesthesia)  - and thoughts about 'what would happen if..?'. There was some good thinking going on, which tells me that the day was a success.

Just which of these local children will turn out to be world-class scientists I can't answer, but I would like to think that it has shown some of them that science covers a huge area of application.  Thank you Liz for organizing it.

I'll be conferencing next week so blogging might be a bit hit-or-miss, but I'm sure I'll return with lots of blog-fodder for the holiday period.

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